Anionic N ₁₈ Macrocycles and a Polynitrogen Double Helix in Novel Yttrium Polynitrides YN ₆ and Y ₂ N ₁₁ at 100 GPa

Two novel yttrium nitrides, YN6 and Y2N11, were synthesized by direct reaction between nitrogen at 100 GPa 3000 K in a laser-heated diamond anvil cell. High-pressure synchrotron single-crystal X-ray diffraction revealed that the crystal structures of Y2N11 feature unique organization atoms—a previously unknown anionic N18 macrocycle polynitrogen double helix, respectively. Density functional theory calculations, confirming dynamical stability compounds, show an anion-driven metallicity, explaining unusual bond orders units. As charge state helix is different from found Hf2N11 because macrocycles have never been predicted or observed, their discovery significantly extends chemistry polynitrides.